“Fifteen minutes?” She was momentarily flabbergasted. “I don’t know. I do not know what you are driving at, Comrade Detective. I heard the noise, let me think, yes, I heard the noise, and I went over.”

“Don’t be nervous. We don’t punish innocent people,” Yu said. “Did something else happen in the lane that morning?”

“No, nothing I can remember.”

“Take your time. Try to recall every detail, from the moment you picked up the frozen shrimp supply from the market. It might have been trivial, perhaps an unexpected sound in the lane, or something else that distracted you.”

“A sound-let me think-yes, I do remember now. There was some noise coming from the green-onion-cake booth. It’s always a noisy place. Lei hawks his wares at the top of his voice, you know. But that morning the noise was louder, mixed with another voice. So I stepped out to the main lane to take a quick look.”

“How long did that take?”

“I don’t know. One minute. A couple of minutes, maybe. From where I stood, I could not hear clearly. It took a little time for me to make out what was happening.”

“Did you walk up to the booth?”

“I took a few steps in that direction, but I never went really close to it, not with my hands covered in shrimp slime.”

“Don’t move, Comrade Peng,” Yu said, standing abruptly. “I’ll be right back.”

He strode to the front lane entrance, and came back with Lei following him, his hands covered in flour. The shrimp woman, her face now a mask of anxiety, was unaware that she was crushing a shrimp to a pulp between her fingers.

“Did you have an argument or a quarrel with somebody on the morning of February seventh, the morning Yin was murdered?” Yu asked.

“Yes, I did. Some bastard complained about a piece of hair in his onion cake, and he demanded ten Yuan as compensation. That’s bullshit. He could have put his own hair into his food. Anyway, we don’t claim to be a five-star restaurant!”

“Do you remember the time?”

“Quite early. Around six thirty.”

So the shrimp woman’s statement was true.

One fact was now established: there had been three or four minutes that morning during which somebody could have left through the back door without being seen.

Yu crossed off Lei from Old Liang’s suspect list, since at least his time was now accounted for.

It was far from a breakthrough, though. This merely made it possible, in theory, to consider an outsider as the murderer.

Yu thanked Peng and Lei. The shrimp woman grasped Yu’s hand in gratitude, forgetting about hers being wet and dirty.

Lei insisted on treating Yu to a brown bag full of his hot green-onion cakes. “Yin was a good woman. We will do whatever we can to cooperate with your investigation. As long as you are working in the lane, breakfast and lunch are on me. Free. But for her help, I would not have my business today.”

Savoring a hot cake stuffed with chopped green onion and minced pork fat, Yu returned to the neighborhood committee office, where Old Liang was waiting with excitement written all over his face.

“A breakthrough, Comrade Detective Yu!”

“What?”

“Remember Cai, the cricket gambler we discussed yesterday?”

“Yes, I do. Is there new information about Cai?”

“I have been working hard on the background checkups, as I told you,” Old Liang said, pouring out a small white porcelain cup of Dragon Well tea for Yu, and then another for himself. “This is extraordinary, excellent tea; all the tea leaves were picked and processed before the Yuqian festival. I keep it for special occasions, like today. It’s really special.”

“Oh, yes. Please tell me what you have found out,” Yu said. “You surely have done a great job. The older the ginger, the spicier.”

On the first day of the investigation, before Yu’s arrival, Cai had told Old Liang that on the morning of February 7, he was not in Treasure Garden Lane, but at his “nail” room in Yangpu District, and that his mother would support his alibi. Old Liang had tried to call the mother, but was told that public phone service there had been canceled several months earlier, as part of the government’s pressure to force out those “nails.” Old Liang did not let the matter drop; he himself went to the nail room. Cai’s mother was not there-and, according to her neighbors, living conditions in the area were so hard that she had long since moved out to stay with her daughter. On the night of February 6 and then on the morning of February 7, no one had seen Cai at that address. As there was only one common sink with running water in the building, residents encountered one another several times a day. They had not seen him, however, for at least a week.

Old Liang had another talk with Cai, who clung to his earlier statement. Instead of contradicting him, earlier that morning Old Liang insisted on walking with him back to his nail home in Yangpu District. When the door was opened, the mail that had accumulated there for over a week stared Cai in the face. One unopened letter bore the stamped date of January 25. Cai had no explanation. Old Liang immediately took Cai into custody, and re-approached his wife and mother-in-law. They continued to swear that Cai had not been in the shikumen building on the morning of February 7, although they could not say where he might have been. They also proclaimed his innocence-which, of course, had no effect on the investigation. All suspects were “innocent.”

“Walking him back to the nail room was really a master stroke,” Yu commented.

“Cai has a motive,” Old Liang said. “As an addicted gambler, he may have been desperately short of money. Cai has that history. And even more important, Cai has a key to the house. He could have sneaked into Yin’s room to steal, not knowing that she would come back earlier than usual, then murdered her, and run upstairs. I don’t think we can rule out the possibility that his wife and mother-in-law are attempting to cover up for him.”

“What did he say after you had destroyed his alibi?”

“He denied having anything to do with the murder,” Old Liang said. “Don’t worry, I have ways of cracking such nuts.”

“Cai is a suspect, I agree,” Yu said. “But I have just a couple of questions. Somebody like Cai bets big-time, thousands or ten-thousands of Yuan on a little cricket, as you have told me. Yin seems to be too small a fish for someone with his appetite.”

“No, I disagree. When you’re desperate, you’re desperate. As an incorrigible gambler, if he had lost several cricket fights in a row, he might have done anything for a few hundred Yuan.”

“It’s a possibility. But why should he have given a false alibi? It didn’t help him at all.”

“Well, you remember the saying, If you had not stolen, you would not be so nervous.”

“Yes, you have a point,” Yu said. “We’ll work on him.”

Yu told Old Liang about his discovery, the possibility that someone could have left through the back door without being seen by the shrimp woman.

Old Liang, proud of his own breakthrough, brushed aside that possibility. “Let’s say there was an opportunity to leave unseen for two or three minutes at most. So the murderer must have waited somewhere in the shikumen house for his chance. But where could he have waited without being seen?”

Detective Yu did not have an answer, not immediately.